Variable condenser



' (1 74 March 1,1927. C' N CAHUSA ,618.9

VARIABLE CONDE-NSER Filed April 16. 1925 1 5' s 35 'i 23 I il l a4 .a0 I `20 1 22 21 I .az 32 2e. 19 l 3.9 QLN... .151g 14 .254.0

Patented Mar. 1r, 1927.

' jUNITE'D STATES Murr.NT Vol-lflcr..

f n N. cAHUsAqoE NfEwAnxQNEW JEnsEY, As`s IGNoR To U. s. 'fr ooL COMPANY,

' v INc., or NEWARK, NEW JERsEY, A 4CORPORATION or NEW JERSEY.

VARIABLE co'NDENsEa.

1- v,-fAmumatio11 mea April 16, 1925. serial No. 23,471.

f' 'invention'.relates to variable condensers, as usedV `in connection with radio apparatus, andhhasoneof its several objects v"to provide fa condenser having means ,to 1 adjust the stator plates, as a unit, laterally with vrelation to the rotor plates so that the ioy latterinay be correctly v'centered and a uniform Vair y gap maintained.

A further feature is in the provision of a-brakingdevice applied to the rotor shaft in such manner as to not only prevent excessive motion, due to centrifugal effect, but also operate to retain the rotor plates in 'Y adjustment, irrespective of jars or vibrations that maybe imparted to the instrument.

These and other allied yaims and objects f are attained by the novel construction and combination of parts hereinafter described and shown v1n the annexed drawings, formlng an essential part of thi-s disclosure, and

Figure 1 is atop plan view of a variable condenser made in conformity with the inj 4a fragmentary part of a radio panel, designated by the numeral 5, having on its outer surface a conventional type of dial 6 controlled by an actuating knob 7.

The dial and knob are fixed on the extend- 'ing end of a spindle/8 rotatably supported in a frame composed of three generally triangular plates, respectively 9, 10 and 11, the latterjof which is composed of a dielectric material, as hard rubber, indurated fiber bakelite, etc.

The other plates are of metal and the kfront plate 9 is held against the inner sur- .face of the panel 10 by a nut 12 threaded on the spindle and Opposed to a similar nut l13 on the opposite side of the panel, these nuts being used to secure the spindle in longitudinal adjustment.

Adjacent the nut 12 is a collar or hub 14, held adjustably on the spindle 8 by a set screw or like fastening, and on which is a thin friction disc 15 of hard rubber or similar material, the purpose of which will later be explained.

, A segmental stop` plate 16` is clamped against the inner end of the 'collar 14 by a nut 17, 'this plate having the vend edges of its segmental portion adapted .to make contact with a fixed pin18 extending from the frame plate 10, thus limiting the rotary motion that can be imparted to the spindle and its attached parts.

A bushing 19 is rigidly fixed in the plate 10 to extend towards the plate 11 and adjacent the bushing is a collar 20 fixed on the spindle 8, and a seriesof rotor plates 21, held at equal distances by spacers 22, are pressed against the collar 20 by another collar 23 clamped by a nut 24 on the outer portion of the spindle.

Between the plates 9 and 10 are spacers 25 through which pass screws 26, their heads being countersunk in the plate 9 and their threaded ends engaged in nutsv 27 fixed rigidly in recesses in the outer ends of dielectric cylinders 28, having solid centers and which are thus drawn firmly against the side of the plate 10 opposite the spacers 25.

Set in recesses in the opposite ends of the cylinders 28 are similar nuts 29 in which are engaged the screw-threaded ends 30 of polygonal bars 31, the screws being held in adjustment by lock nuts 32; the opposite ends of the bars are reduced and fitted to pass through openings in the dielectric plate 11, which is drawn against the shoulders of the bars by crown nuts 33.

A series of annular grooves 34 are formed in the bars 31 at regularly spaced intervals and secured in these grooves are stator plates 35, which, by turning the bars 31 can be adjusted relatively to the intermediate rotor plates to produce uniform air gaps.

The brake device consists of a stud 36 fixed rigidly on the plate 10 to extend towards the panel, its outer end being adapted to receive a screw 37 clamping a collar 38 against a pair of thin spring discs 39 and 40, the peripheral edges of which are oppositely outturned and adapted to receive between them the edge portion of the friction disc 15 so that as the latter is rotated by the knob actuated spindle together with the rotor plates, a binding effect is obtained which may be adjusted by the screw 37.

It will be understood that the spring discs 39%() rotate by Contact with the friction disc and at all times press yieldably against its opposite sides so as to Vpresent an eiiicient brake or drag effect sufficient to prevent eX- cessively free rotation of the rotor plates and retain them in adjustment, Vthe additional impedance however being'V insufficient to be noticeable in operating the dial and obviously the action is quite smooth and regular.

Although I have described my improve-V ments with considerable detail and with respect to certain particular forms of my invention, I do not desire to be limited to such details since many changes and modifloat-ions may well bc made without depart-- ing from the spirit and scope of my invention in its broadest aspect.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

A variable condenser comprising a frame composed of a rear dielectric plate, front and intermediate metal plates, connections between said metal plates whereby they are firmly bound together, said connections comprising dielectric cylinders having nuts iixed in their ends, .insulated bars engaging said nuts at one end, clamp screws holding the cylinders against the intermediate plates, stator plates fixed in uniform spaced grooves in the insulated bars, interjacent the rotor plates, and means for clamping the sections of said connections when in adjustment.

CLARENCE N. CAHUSAC. 

